Breeding biology of Saunders's tern (Sterna saundersi) in the Farasan Islands, Kingdom of Saudi Arabia

Abstract

Saunders's terns (Sternula saundersi) are a small, ground-nesting marine bird species that have a massive rearing range, including the shores and islands of Asia and Africa adjacent to the north Indian Ocean. Despite occupying a large breeding range, little is known about the breeding ecology of this species. This research explored aspects of Saunders's terns' breeding ecology and predation rate in 2013 on the Farasan Islands of Saudi Arabia. The outcomes confirm that the mean clutch size of a Saunders's tern was 1.77 ± 0.08 (n = 31) eggs per clutch and the mean egg size was 31.05 × 23.15 mm. The results of this study show a remarkable relationship between clutch size and egg volume and length (p = .002, p = .004, respectively). Predation was the major reason for nest damage (62.5%). Evidence from cameras at nests showed that the predators of Saunders's tern nests on the Farasan Islands were white-tailed mongoose (Ichneumia albicauda) and Egyptian vultures (Neophron percnopterus). This is the first study on the breeding ecology of Saunders's terns, and it shows that predator control is essential to the existence of the species. The results of this study suggest that fencing some breeding sites may help to minimize human disturbance and decrease the risk of nest predation from mammalian predators. Further research is needed to compare the predation rates on the mainland and islands and to develop efficient strategies to conserve this ground-nesting species.

Keywords: Breeding Biology; Farasan Islands; Predation; Saudi Arabia; Saunders’s tern.

Fig. 1

Map of the Farasan Islands, Red rectangle displaying the Saunders’s tern study site.

Fig. 2

Showing the cameras coloured with clay-coloured paint to become invisible in the environment surrounding the nests.

Fig. 3

The nest site selection and nest materials of Saunders’s terns.

Fig. 4

One parent would brought prey (small fish) for its mate, who was incubating the eggs.

Fig. 5

Showing mongooses and Egyptian vultures prey on nests of Saunders’s terns.